Our work is on gene expression in eukaryotic organisms and the mechanisms which control this expression. We are attacking this in three separate projects. One project deals with the mechanism of the termination of transcription in eukaryotes. We will determine the nucleotide sequence of the terminating end of the mRNAs in the region just preceding the poly(A) tract in a spectrum of organisms, yeast, sea urchins, chickens, etc. We will see whether there is indeed a common terminating sequence like the -GCAAU- we identified tentatively in yeast some years ago. We are especially interested in seeing if these eukaryotes show a more extended common sequence like the -CAAUCAAA found recently by Rosenberg and Landy and their groups as the authentic terminating sequence in E. coli. A second project deals with the control of actin synthesis in the sea urchin embryo, the translation of the stored actin mRNA in the egg before and after fertilization, and the appearance of new actin mRNAs during cleavage. A third project deals with the same controls in the case of tubulin synthesis in the cleaving sea urchin embryo.